Technical Field
The present invention concerns an anchoring section for anchoring a pylon of a wind power installation in a foundation. The present invention also concerns a substructure of a pylon of the wind power installation. The invention further concerns a wind power installation and a method of anchoring a pylon of a wind power installation.
Description of the Related Art
A modern wind power installation has a pod with an aerodynamic rotor. The pod is carried on a pylon and the pylon is anchored in a foundation and carried thereby. FIG. 6 shows such a wind power installation. Nowadays pylons of wind power installations can reach a height of over 100 meters (m). The diameter of the aerodynamic rotor can also reach a diameter of over 100 m. Pylons of such wind power installations are usually made from steel and/or prestressed concrete and are enormous in weight. Added to the weight of the pylon is the weight of the pod which in the case of a gearless wind power installation can have a generator of a diameter of 10 m or even more and is of a corresponding weight which has to be carried by the foundation in addition to the weight of the pylon itself. In addition in operation of the wind power installation an enormous wind pressure applies a loading to the aerodynamic rotor and that wind pressure is ultimately passed by way of the pylon to the foundation and can there result in a tilting moment.
An anchorage for the pylon in the foundation has to carry all those loadings and pass them to the foundation without damaging the foundation or in such a way that any damage is minimized.
To anchor a steel pylon it is known for a steel section which can also be referred to as the anchoring section to be partially let into the foundation, that is to say into the concrete of the foundation, in order to fix the pylon on that anchoring section. A lowermost pylon section of a pylon is thus fixed on that anchoring section.
Such an anchoring section can basically be in the form of a T-shaped bearer which is curved to form a circle and which is concreted in place upside down, in relation to the letter T. Thus when the anchoring section is appropriately anchored in place the anchoring section has at its lowermost end a horizontal, peripherally extending flange portion (which gives the T-shaped bearer its name) and by way of which the loads occurring are transmitted into the foundation. A part of that anchoring section then projects beyond a surface of the foundation, that is to say beyond a concrete surface. That portion protruding beyond the surface, to carry loads, can have a further, peripherally extending portion, in particular a flange portion, to fix said lower pylon section thereto.
A problem with that form of anchorage is that in particular the application of load by way of the lower horizontal peripherally extending flange can lead to damage to the foundation. Expressed figuratively there is the risk, in the worst-case scenario that the anchoring section presses away in a funnel shape, a region of the concrete foundation, that is beneath the lower flange, or that at least corresponding fracture locations, fracture regions or crack regions occur in the foundation. In that respect a particular problem is that such damage can occur in the lower region of the foundation and can therefore be difficult to detect. In addition in the case of crack formation there is already the problem that water can penetrate into the crack and thus into the foundation and can worsen the damage to the foundation.
In the same manner a tensile loading occurring due to a tilting force can lead to a similar local loading in the upper region of the foundation because in that case also the lower horizontal flange can lead to a concentrated application of load. Another problem is that movements can be transmitted to a reinforcing bar in such a way that this can lead to spalling phenomena in the concrete at a top side of the foundation.
The German Patent and Trade Mark Office searched the following state of the art in the priority application: DE 20 2010 005 965 U1, WO 2008/087181 A1, DE 102 26 996 A1, WO 2011/029994 A1 and DE 25 44 657 A1.